Steering plasmon beam from a point source.

We extend the phase modulation method by in-plane diffractions from plane wave incidence to point source of surface plasmon polariton (SPP). A well-defined SPP focus is successfully realized from a point source under the diffraction by a carefully designed nanohole array, which is easy to layout in the future integrated optical circuits. With this method, the SPP Airy beam and finite plane wave are demonstrated as well, proving a general applicability of this modulation method. The proposed method and realized functions are expected of benefits for the future integration optics.